UPGRADING REPAIRING PCs

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164 Chapter 5—Floppy, Removable, Tape, and Flash Storage Other Tape Drive Problems Other issues that might cause problems in general with tape backups include • Corrupted data or ID information on the tape. • Incorrect BIOS (CMOS) settings. • Networking problems (outdated network drivers and so on). • The tape was made by another tape drive. If the other drive can still read the tape, this might indicate a head alignment problem or incompatible environment. Tape Retensioning Retensioning a tape is the process of fast forwarding and then rewinding the tape to ensure even tension exists on the tape and rollers throughout the entire tape travel. Retensioning is recommended as a preventive maintenance operation when using a new tape or after an existing tape has been exposed to temperature changes or shock (for example, dropping the tape). Retensioning also restores the proper tension to the media and removes unwanted tight spots that can develop. Some general rules for retensioning include the following: • Retension any tapes that have not been used for over a month or two. • Retension tapes if you have errors reading them. • Retension any tapes that have been dropped. • In some cases, it might be necessary to perform the retension operation several times to achieve the proper effect. Most tape drive or backup software includes a Retension feature as a menu selection
Chapter 6 Serial Ports and Modems 6 Understanding Serial Ports The asynchronous serial interface was designed as a system-tosystem communications port. Asynchronous means that no synchronization or clocking signal is present, so characters can be sent with any arbitrary time spacing. Each character that is sent over a serial connection is framed by a standard start-and-stop signal. A single 0 bit, called the start bit, precedes each character to tell the receiving system that the next eight bits constitute a byte of data. One or two stop bits follow the character to signal that the character has been sent. At the receiving end of the communication, characters are recognized by the start-and-stop signals instead of by the timing of their arrival. Serial refers to data that is sent over a single wire, with each bit lining up in a series as the bits are sent. This type of communication is used over the phone system because this system provides one wire for data in each direction. Compared to parallel ports, serial ports are very slow, but their signals can be transmitted a greater distance. The other wires in the serial port are used to control the flow of data to or from the port. Serial ports are also referred to as COM ports because they are used to communicate between devices. Physically, serial ports come in two forms, although through adapters or specially-wired cable, they have no problems communicating with each other. The following figures show the standard 9-pin (see Figure 6.1) and 25-pin (see Figure 6.2) serial ports. The 25-pin serial port has pins sticking out, as opposed to the 25-pin parallel port, which has holes for pins.
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UPGRADING AND REPAIRING PCs TECHNIC
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Associate Publisher Greg Wiegand Se
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Contents 1 General Technical Refere
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Contents vii IDE Hard Drive Identif
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Serial Port Configuration 172 Avoid
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Contents xi Sound Quality Standards
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About the Authors Scott Mueller is
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watch, photograph, and (occasionall
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Tell Us What You Think! As the read
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Chapter 1 General Technical Referen
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Understanding Bits, Nibbles, and By
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Note Glossary of Essential Terms 5
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Glossary of Essential Terms 7 Table
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Glossary of Essential Terms 9 Table
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Table 1.5 Hexadecimal/ASCII Convers
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Hexadecimal/ASCII Conversions 13 Ta
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Table 1.5 Hexadecimal/ASCII Convers
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Hexadecimal/ASCII Conversions 17 Ta
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20 Chapter 2—System Components an
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36 Caution Chapter 2—System Compo
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38 Table 2.15 Troubleshooting Power
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44 modules can be divided by 9, but
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50 Other Add-On Card Configuration
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Chapter 3 3 BIOS Configurations and
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Where BIOS Updates Come From 71 Tab
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How to Recover from a Failed BIOS U
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Note A complete list of PnP device
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Other BIOS Troubleshooting Tips 77
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Determining the Motherboard Manufac
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Determining the Motherboard Manufac
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Table 3.8 Common Keystrokes Used to
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Phoenix BIOS Beep Codes The followi
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Port 80h Beep Code Codes Error Mess
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BIOS Configuration Worksheet 89 BIO
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BIOS Configuration Worksheet 91 Sha
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4 SCSI and IDE Hard Drives and Opti
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Cable key prevents improperly plugg
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Breaking the 504MB (528-Million-Byt
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Table 4.3 Using LBA Mode Operating
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5. Use the #4 option—View Current
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Using LBA Mode 103 Table 4.6 Why ID
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Sources for BIOS Upgrades 105 Table
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Improving Hard Disk Speed 107 Figur
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Bus-Mastering Chipsets for IDE 109
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Table 4.13 Bus-Mastering Chipsets b
Page 131 and 132: Table 4.14 Other IDE Drive Installa
Page 133 and 134: standard single-ended SCSI devices
Page 135 and 136: SCSI Drive and Device Configuration
Page 137 and 138: SCSI Drive and Device Configuration
Page 139 and 140: Following these tips will help mini
Page 141 and 142: SCSI Configuration Troubleshooting
Page 143 and 144: Using FDISK 125 Using FDISK FDISK i
Page 145 and 146: Benefits of Hard Disk Partitioning
Page 147 and 148: How FDISK and the Operating System
Page 149 and 150: How FDISK and the Operating System
Page 151 and 152: Now, the operating system can use t
Page 153 and 154: The command switches are explained
Page 155 and 156: MS-DOS Command-Line Access to CD-RO
Page 157 and 158: • Make sure the drive shows up as
Page 159: Troubleshooting Optical Drives 141
Page 162 and 163: 144 Chapter 5—Floppy, Removable,
Page 174 and 175: 156 • OnStream’s ADR (Advanced
Page 178 and 179: 160 Table 5.13 High-Performance Tap
Page 184 and 185: 166 Chapter 6—Serial Ports and Mo
Page 186 and 187: 168 Table 6.2 25-Pin (PC, XT, and P
Page 188 and 189: 170 Table 6.4 Overview of UART Chip
Page 206 and 207: 188 (These settings require changes
Page 208 and 209: 190 Chapter 7—Parallel Ports, Pri
Page 210 and 211: 192 Building a Parallel Loopback Pl
Page 222: 204 Chapter 7—Parallel Ports, Pri
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